1. Field of the Invention
The present invention relates to a growth promoting agent for the root of a plant whose roots, stems and leaves can be distinguished each from the other two. More specifically, this invention relates to a plant-root growth promoting agent comprising inosine as the effective ingredient and also to a method for promoting the root growth of such a plant, which method comprises applying inosine as the effective ingredient thereto, as well as to the plant bodies, including leaves of leaf vegetables and fruit of fruit vegetables, of plants to which such a plant-root growth promoting agent has been applied during their life time.
2. Discussion of the Background
Several examples where a nucleic acid-related substance is applied to plants are conventionally known.
For example, in (a) Japanese Patent Publication kokoku No. 22919/1964 is disclosed a plant growth regulator which comprises, as effective ingredients, .beta.-indoleacetic acid or the like and at least one substance selected from the group consisting of a purine base, pyrimidine base, nucleoside and nucleotide, each available by the decomposition of nucleic acid.
In the above plant growth regulator, however, nucleic acid bases, nucleosides and nucleotides which are obtained by the decomposition of nucleic acid and differ in the decomposition degree are treated as substances having the same effects(i.e., equivalents). As is apparent from the disclosure therein that these decomposition products of nucleic acid except some products belonging to purine base do not have substantial plant growth regulating action, the plant growth regulator is a composition which requires, as the essential condition, the combined use of a nucleic-acid decomposition product and .beta.-indoleacetic acid or the like. In addition, the plant growth regulator is applied by (1) immersing seeds, radicles or seed tubers in a solution of the regulator; (2) spraying the solution to young fruit bodies of mushroom, young fruits, floral organs or phylloplanes; or (3) employing the above two treatments in combination at appropriate times selected as needed (for example, subjecting seeds to the immersing treatment, and then the phylloplanes of the plants grown from the seeds to the spraying treatment), which treatments are utterly different from the application method according to the present invention in which the growth promoting agent is applied in such a way that it promotes directly the growth of plant roots.
In (b) Japanese Patent Publication kokoku No. 16310/1974 is disclosed a growth regulator for fruit vegetables which comprises, as effective ingredients, a plant hormone such as chlorophenoxyacetic acid and at least one substance selected from the group consisting of non-decomposed nucleic acid pyrimidine bases, purine bases, nucleosides and nucleotides, the last four being obtainable by the decomposition of nucleic acid.
In this growth regulator for fruit vegetables, however, non-decomposed nucleic acid per se and various decomposition products thereof different in decomposition degree are put in the same category and besides, as is apparent from the disclosure therein that these nucleic-acid related substances are used in order to reduce the generation of various physiological disorders of crops caused by the application of the above-described plant hormone and to increase the expected effects to be brought by the application of the plant hormone, the combined use of a plant hormone and a nucleic-acid related substance is the essential condition. In addition, a solution of the above growth regulator for fruit vegetables is desired to be distributed onto the plant body; this distribution treatment is effected at the flowering season to such an extent of wetting the flower clusters or flower organs with the solution by spraying the solution with the use of a sprayer over the flower clusters, the flower organs or the whole crop or by coating or immersing the flower clusters or flower organs with or in the solution. These treatments are utterly different from the application method of the plant-root growth promoting agent of the present invention.
In (c) Japanese Patent Publication kokoku No. 17670/1979 is disclosed a method for improving the leaf life of a foliage plant, which comprises bringing the leaves, the leaf stems or petioles, or the cut ends thereof, of a matured foliage plant into contact with one or more than one of nucleotides and nucleosides (inosine being given as an example).
Also in the above method for improving the leaf life of a foliage plant, however, various nucleotides and nucleosides are put in the same category and a solution of effective ingredient(s) is applied as described above, which application is utterly different from the method according to the present invention.
In (d) Japanese Patent Application Laid-Open kokai No. 56759/1973 is disclosed a method for promoting the germination of pollen of a fruit tree, which comprises spraying the flower buds of the fruit tree at its bud time with a single solution or a mixed solution of at least two of nucleotides, nucleosides (inosine being given as an example) and nucleic acid bases.
Also in the above method for promoting the germination of pollen of a fruit tree, however, various nucleotides and nucleosides are put in the same category and in addition, a solution of the effective ingredient(s) is applied as described above, which application is utterly different from the application method of the present invention.
In (e) Japanese Patent Laid-Open kokai No. 68848/1985 is disclosed a method for prolonging the life of cut flowers, which comprising applying a mixed solution of inosine and calcium chloride (as a liquid used for natural flowers displayed at a flower shop or a liquid poured in a flower bowl or vase) onto natural flowers.
In the above method for prolonging the life of cut flowers, however, the combined use of inosine and calcium chloride is the essential condition and moreover, the application method of the effective ingredients is utterly different from that of the present invention.
As has been described above, the use of nucleic-acid related substances for plants is conventionally known, but in the said use, the combined use of these substances with other substance is the essential condition. Even if various nucleic-acid related substances are used singly, they are put in the same category without being distinguished from each other. In addition, the application method of effective ingredients is utterly different from that of the present invention.